Method for automatically reclosing and an automatic reclosing device

ABSTRACT

The invention relates to a method for automatically reclosing when there is a short-circuit in a line section of an electric energy supply line, whereby said section is defined by one switch respectively which comprises an allocated short-circuit detection device. According to the inventive method and after the switches have been released by a short-circuit, a reclosing instruction that is produced on the one end of the line section trips the switch on the other end. The aim of the invention is to carry out said method in such a way that the switch is treated with care as far as possible. The switch ( 6 ) on the other end ( 5 ) of the line section ( 2 ) is tripped after a predetermined time delay provided that the short-circuit in the line section terminates during the time delay.

[0001] The invention relates to a method for carrying out an automatic reclosure when there is a short-circuit in a line section, limited in each case by a breaker with associated short-circuit detection device, of an electric energy supply line, in which line section after the breakers have been tripped due to a short-circuit, the breaker at the other end has been intertripped by a reclosing command generated at one end of the line section.

[0002] A method of this type is known from the book by H. Titze “Fehler und Fehlerschutz in elektrischen Drchstromanlagen”, [Faults and Fault Protection in Electrical Three-phase Systems], Vol. 2, 1953, pp. 223 to 227, particularly page 227. In this known method, a breaker having in each case one short-circuit detection device is provided at each end of a line section of an electrical energy supply line to be monitored; if the short circuit detection devices detect a fault in the line section to be monitored, they actuate the associated circuit breakers by means of a tripping signal whereupon the breakers open by separating the line section from the energy supply line. A reclosing device, particularly a reclosing relay, ensures that the breaker at the one end of the line section is closed again after a short time by delivery of a reclosing command; during this process actuation of the reclosing device also trips the breaker at the other end of the line section and thus also closes it. In the known method, therefore, the two breakers at the ends of the line section to be monitored are reclosed quasi-synchronously.

[0003] The invention is based on the object of developing the known method in such a way that the breakers are reclosed with the greatest possible care.

[0004] According to the invention, to achieve this object in a method of the type initially specified, the breaker at the other end is intertripped with a predetermined time delay if the short-circuit has already ended at the beginning of the time delay. The invention is not restricted to only one further or other end being allocated to one end of the line section but can also be applied in the case of those line sections from which branch lines diverge which are in each case limited with a breaker at their end facing away from the one end of the line section.

[0005] An essential advantage of the method according to the invention consists in that the breakers of the line section to be monitored are operated with as much care as possible. This is attributable to the fact that in the method according to the invention, reclosing is initially only carried out with respect to the breaker at one end of the line section. If after this reclosure the associated short-circuit detection device still finds a short-circuit, this breaker is opened again by further tripping. During this time, the breaker at the other end of the line section remains unoperated and, therefore, is not switched to a short-circuit which is still in existence and it is thus protected. It is only when a predetermined time delay has elapsed and a short-circuit is not detected at the one end of the line after the reclosure that the breaker at the other end of the line section is switched on. A further advantage of the method according to the invention is obtained by the fact that due to the fact that a simultaneous connection at both ends to a short-circuit which may still exist is prevented, the system stability is impaired to a lesser degree.

[0006] In an advantageous embodiment of the method according to the invention, the breaker at the other end is intertripped by having applied to it an intertripping signal which is delayed by the predetermined time delay with respect to the reclosing command and which is derived from the reclosing command.

[0007] It has also been found to be advantageous if the intertripping signal is generated if, after the occurrence of the reclosing command, the predetermined time delay has occurred without further tripping having been initiated at the one end of the line section by the short-circuit detection device.

[0008] The invention is also related to a reclosing device at one end of a line section, limited by in each case one breaker with associated short-circuit detection device, of an electrical energy supply line, with an output for delivering a reclosing command to the breaker at one end of the line section and with an output chip for outputting an intertripping signal to the breaker at the other end of the line section.

[0009] To achieve a breaker-protecting operating mode with such a reclosing device, the output chip is connected at its input to the output of the reclosing device, according to the invention, and exhibits a time delay element which delivers a status signal after a predetermined time delay has elapsed; the time delay element is connected to one input of a logic circuit which is connected with another input to an output of the short-circuit detection device of one end of the line section, and the output of the logic circuit is connected to the breaker at the other end of the line section via a communication channel.

[0010] An essential advantage of the reclosing device according to the invention is seen in the fact that it can be used for obtaining a time-delayed intertripping signal, which contributes to the breaker protection, in a comparatively simple manner, that is to say with little circuit expenditure.

[0011] To expand the invention in greater detail, the FIGURE shows the elements of an arrangement with a reclosing device which are essential for carrying out the method according to the invention.

[0012] The FIGURE shows an electrical energy supply line 1 which contains a line section 2. This line section 2 is limited at its one end 3 by a breaker 4 and at its other end 5 by a breaker 6.

[0013] The breaker 4 at the one end 3 is associated with a short-circuit detection device 7 which detects, in a manner not shown, current and voltage at the electrical energy supply line 1 or the line section 2, respectively, and in the case of a short-circuit, generates from these detected quantities at its output 8 a tripping signal A1 which brings the breaker 4 into an open position shown, via a connection 9 drawn diagrammatically. Accordingly, the breaker 6 is associated at its other end 5 with a further short-circuit detection device 10 which also generates a tripping signal A2 at its output 11 from the currents and voltages at the energy supply line if a short-circuit has occurred in the line section 2; following the tripping signal A2, the breaker 6 is brought into the open position shown.

[0014] Since a short-circuit on an energy supply line, particularly an open-wire line, is frequently formed by an arc, the so-called method of automatic reclosure has been carried out for a long time. In the arrangement for carrying out the method according to the invention, shown in the FIGURE, this is done in the following way:

[0015] If a tripping signal A1 has been generated by the short-circuit detection device 7 at its output 8, this tripping signal is also supplied to an input 12 of a reclosing device 13. After a predetermined time, this reclosing device 13 generates at its output 14 a reclosing command W by means of which the breaker 4 is closed. With the generation of the switch-on command W a delay element 15 of the reclosing device 13 is started which supplies a status signal ME to a logic circuit 17 via an input 16 after a predetermined time delay. A further input 18 of the logic circuit 17 is directly connected to the input 12 of the reclosing device 13 and therefore has applied to it the tripping signal A1. The delay element 15 and the logic circuit 17 form one output chip 19.

[0016] The logic circuit 17 or, respectively, the entire output chip 19 are designed in such a manner that an intertripping signal MS only occurs at an output 20 of the output chip 19 or of the reclosing device 13, respectively, if during the time determined by the delay element 15 in accordance with the predetermined time delay, the short-circuit detection device 7 has not delivered another tripping signal via its output 8. This is the case if a short-circuit is no longer found after the breaker 4 has been reclosed. There is then no longer a short-circuit on the line section 2, so that the breaker 6 at the other end 5 of the line section 2 is closed protectively—without switching to a short-circuit—by the intertripping signal MS.

[0017] If, in contrast, the short-circuit detection device 7, after having delivered the reclosing command W to the switch 4, and thus after this breaker has been closed, finds that the short-circuit still exists on the line section 2, a further tripping signal is formed at the output 8 by means of which not only is the breaker 4 opened again but the delay element 15 is also reset again so that the status signal ME is no longer produced at its output. As a consequence, the intertripping signal MS also does not occur at the output 20, and the breaker 6 remains open. 

1. A method for automatic reclosure in the case of a short circuit on a line section, limited in each case by a breaker with associated short-circuit detection device, of an electric energy supply line, in which after the breakers have been tripped due to a short circuit, the breaker at the other end is intertripped by a reclosing command generated at one end of the line section, characterized in that the breaker (6) at the other end (5) is intertripped with a predetermined time delay if the short-circuit has already ended at the beginning of the time delay:
 2. The method as claimed in claim 1, characterized in that the breaker (6) at the other end (5) is intertripped by having applied to it an intertripping signal (MS), delayed by the predetermined time delay with respect to the reclosing command (W) which is derived from the reclosing command (W).
 3. The method as claimed in claim 2, characterized in that the intertripping signal (MS) is generated if the predetermined time delay has occurred after the occurrence of the reclosing command (W) without any further tripping having been initiated by the short-circuit detection device (7) at one end (3) of the line section
 2. 4. A reclosing device at one end of a line section (2), limited by in each case a breaker (4, 6) with associated short-circuit detection device (7, 10), of an electrical energy supply line (1), with an output (14) for delivering a reclosing command (W) to the breaker (4) at one end (3) of the line section (2) and with an output chip (19) for delivering an intertripping signal (MS) to the breaker (6) at the other end (S) of the line section (2), characterized in that the output chip (19) is connected at its input to the output (14) of the reclosing device (13) and exhibits a time delay element which delivers a status signal (ME) after a predetermined time delay (15) has elapsed, the time delay element (15) is connected to an input (16) of a logic circuit (17) which is connected with another input (18) to an output (8) of the short-circuit detection device (7) of one end (3) of the line section (2), and the output (20) of the logic circuit (17) is connected to the breaker (6) at the other end (5) of the line section (2) via a communication channel (21). 